OsRAC3调控水稻籽粒性状的功能分析

目的 RAC/ROPs是一类植物特有的小G蛋白，作为分子开关参与众多的植物信号转导途径。OsRAC3通过与细胞分裂素信号组分互作，调控水稻Oryza sativa L.冠根发育，但是否影响水稻地上部分的性状尚不清楚。本研究主要分析OsRAC3对水稻穗发育以及产量性状的影响。方法 对水稻OsRAC3promoter::GUS转基因植株的花序组织进行GUS染色，分析OsRAC3的表达模式。分析转基因材料持续激活型突变体(CA-osrac3)和显性失活型突变体(DN-osrac3)2种试验材料的每穗粒数、粒长、粒宽、千粒质量等主要农艺性状。结果 OsRAC3在花序分生组织、雄蕊和雌蕊中强烈表达；CA-osrac3株系的穗粒数减少，籽粒更加饱满，粒长、粒宽、千粒质量均显著高于野生型；DN-osrac3株系的穗分枝数少且育性差，籽粒粒长、粒宽、千粒质量则显著低于野生型。结论 OsRAC3影响水稻穗的发育过程，持续激活型突变体CA-osrac3促进水稻籽粒的发育；OsRAC3在水稻高产育种和遗传改良中具有重要的应用价值。

Functional analysis of OsRAC3 regulating seed traits in rice

Objective RAC/ROPs are a class of plant-specific small G proteins, which are involved in multiple signaling pathways as molecular switches. OsRAC3 regulates rice (Oryza sativa L.) crown root development by interacting with cytokinin signaling components. However whether it affects traits in the aboveground parts of rice remains unclear. This study mainly aims to analyze the effects of OsRAC3 on spike development and yield traits of rice. Method The inflorescence tissue of rice OsRAC3promoter::GUS transgenic plants were stained with GUS to analyze the expression pattern of OsRAC3. We also analyzed the main agronomic traits such as number of grains per spike, grain length, grain width and thousand grain weight of two experimental materials, constitutively activated mutant (CA-osrac3) and dominant negative mutant (DN-osrac3).Result OsRAC3 was strongly expressed in floral meristems, stamen and pistill. CA-osrac3 had fewer grains but its grain length, grain width and thousand grain weight were significantly higher than those of wild-type. DN-osrac3 had a low number of spike branches and poor fertility, while the grain length, grain width and thousand grain weight were significantly lower than those of wild-type.Conclusion OsRAC3 affects the developmental process of rice spikes, and the constitutively activated mutant CA-osrac3 promotes the growth of rice seeds. OsRAC3 has important applications in high-yield breeding and genetic improvement of rice.